Year : 1977 | Volume
: 25 | Issue : 2 | Page : 6--8
SP Dhir1, RC Mahajan2, IS Jain1, MB Chabra2, DN Gangwar1,
1 Department of Ophthalmology, Postgraduate Institute of Medical Education & Research, Chandigarh, India
2 Department of Microbiology, Postgraduate Institute of Medical Education & Research, Chandigarh, India
S P Dhir
Department of Ophthalmology, Postgraduate Institute of Medical Education & Research, Chandigarh
|How to cite this article:|
Dhir S P, Mahajan R C, Jain I S, Chabra M B, Gangwar D N. Ocular toxoplasmosis.Indian J Ophthalmol 1977;25:6-8
|How to cite this URL:|
Dhir S P, Mahajan R C, Jain I S, Chabra M B, Gangwar D N. Ocular toxoplasmosis. Indian J Ophthalmol [serial online] 1977 [cited 2022 Nov 29 ];25:6-8
Available from: https://www.ijo.in/text.asp?1977/25/2/6/31249
Toxoplasmosis as one of the causes of uveitis is well documented. However, the diagnosis of ocular toxoplasmosis is largely presumptive based upon clinical picture and certain laboratory tests. Few reports are available from the country indicating the prevalence of toxoplasma antibody in ocular disorders,,,. We present an analysis of 101 cases of various ocular disorders who were studied for toxoplasma antibody titres.
Material and Methods
101 cases of various ocular disorders attending the Eye outpatient Department of the Postgraduate Institute of Medical Education and Research. Chandigarh, who were referred for toxoplasma antibody titres have been studied.
Serum samples and toxoplasma antibody test:
Five ml. clotted blood samples were obtained in every case and the serum was separated. It was preserved in 1:10,000 thiomersal and stored at-20°C till used.
The tanned red cell haemagglutination test (IHA Test for toxoplasmosis) was done by the method described elsewhere R.H. Strain of toxoplasma gondii maintained in the laboratory was used for the preparation of haemagglutination antigen. Conventional checker board titrations were performed to find out the optimum dilution of the antigen to be used in the routine test.
Patterns of haemagglutination were read after two hours of incubation at room temperature followed by keeping at 4°C overnight. Whenever, heterophil antibodies were present, these were removed by a adsorption with normal sheep red blood cells. Known positive and negative serum controls were always put up simultaneously.
The age and sex distribution of the 101 cases studied is shown in [Table 1].
Results of haemagglutination test in the patients are summarised in [Table 2]. There were 27 cases having a haemagglutination titre of 1:512 or more. They were considered to have a definite toxoplosma gondii infection at present or in the past. The distribution of these cases with clinical diagnosis is seen in [Table 3]. The percentage distribution of cases in anterior, posterior and pan uveitis is almost the same. There were two cases of pan uveitis which presented with a clinical picture of Vogt Koyanagi Harada's Disease. One patient who came with healed central choroiditis had a reactivation during follow up and his antibody titre rose from 1:512 to 1:2048 during the active stage and then declined.
In the miscellaneous group there were three patients who had positive haemagglutination titres. Two patients presented with a clinical picture of heredo-macular degenera tion. Both the patients were young boys and all signs of past or present inflammation in the fundi were absent. Both eyes presented bilateral symmetrical pictures. However, absence of any hereditary history led to investigations for toxoplasmosis. The third patient presented with clinical picture of retinitis pigmentosa.
The prevalence to toxoplasmosis as observed by antibody study in Chandigarh population is 8.1%. 1 However, it is not known as to how many of those with toxoplasma antibody had ocular involvement. The higher prevalence of toxoplasma antibody titres (26.7%) in ocular disorders than in general population is statistically significant. It was seen that 30% of the patients with uveitis of unknown origin had toxoplasma antibody titres 1:512 or above. The 21.9% excess of toxoplasma antibody in uveitis patients of unknown aetiology compared to general poputation points to its importance in uveitis of unknown origin in this part of the country.
Batta in a study conducted in Delhi demonstrated antibodies against toxoplasma by haemagglutination test in 13.1 % of uveitis cases. Parkash studied 327 uveitis patients by the haemagglutination test. He got positive results in 14% of the cases. Malik tested 77 cases of uveitis with haemagglutination test and found that 10 cases i.e., 13% were positive (titre 1:16 or above) Rao and Rao in a study from South India reported positive haemagglutination test (titre 1:4 and above) in 11 out of 57 cases of uveitis of unknown origin i e., 19.3%. The present study reveals a much higher percentage (30%) of positive haemagglutination titre of 1:512 or above.
While there is no good reason to assume that a titre of 1:8 is not indicative of past infection, there is a great disagreement about the minimum haemagglutination titres that should be considered positive, Chord, took a titre of 1:400 or more where as Walls took a titre of 1:200 of more as significant one. In the, present study the doubling dilutions used were 1:8, 1:16, 1:32, 1:64, 1:128 and so on so that an antibody titre of 1:512 or more was considered positive.
A definitive diagnosis of ocular toxoplasmosis can only be made by recognition of the organism or histological examinaion of the enucleated eye. Rarely has the parasite been recovered from the aqueous or sub-retinal fluid during life. In the absence of demonstration of the organism the diagnosis depends indirectly on laboratory evidence of past or present infection in the body. The present study does indicate that toxoplasmosis plays an important aetiological role in uveitis of unknown origin.
101 cases of various ocular disorders referred for toxoplasmosis antibody test have been analysed. 30% cases of uveitis of unknown aetiology were found to have haemagglutination titres of 1:512 or above. This is the highest prevalence of toxoplasmosis antibody titres in uveitis cases so far reported from India. Some of the cases with interesting clinical findings are discussed.
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